Computer aided design of an axial-field PM brushless DC motor for an electric vehicle

Summary form only given. This paper presents the computer-aided design and analysis of a pancake-type three-phase axial-field permanent magnet brushless DC motor meant for the direct drive of an electric two-wheeler. The motor is accommodated inside the rim of the wheel. On comparison of various kinds of permanent magnet motors, it is found that the axial-flux type having sandwiched coil configuration with two-airgaps is the best choice, the advantages being the lack of any axial or thrust load on the bearings, better cooling, better winding utilization, low inductance, reduced torque ripple and acoustic noise, and negligible effect of demagnetization of the permanent magnets. Effects of all machine parameters on the performance of the motor have been studied in detail and the results of this parametric study are provided. Results of the 2-D and 3-D FE analyses conducted on this motor to arrive at the most economical and viable design are also given. The effect of armature reaction is studied in detail using the FE model and the variation in performance is accurately predicted. The entire design procedure is explained in detail with the help of a flow chart. All the steps involved in the design of the motor such as selection of configuration, design of magnetic circuit, selection of materials, calculation of machine parameters and calculation of performance are discussed. Fabrication aspects of the motor components and tuning required for the design for easy fabrication are also discussed.